Two major aspects of the immunobiology of Trichinella spiralis will be investigated: 1). The isolation and characterization of functional antigens from the stichocyte of the mature muscle larva, and the effects of host protection on the enteral stages of T. Spiralis after induction of immunity with stichocyte antigens. These studies will be carried out using a combination of standard protein separatory procedures. Data from these endeavors will contribute to the detailed understanding of the physical and chemical nature of the protective antigens of T. spiralis. Work on the immune effects on adult worm fecundity and longevity will complement the studies on the functional antigens and may reveal more concerning the purposes to which these stichocyte antigens are being put during the worms' life cycle. 2) The relationship between larval infectivity and the development of the Nurse cell in a variety of altered intracellular environments. These studies are designed to expand our knowledge of the pathobiology of T. spiralis infection, and thus lead to the eventual full description of this symbiotic relationship. Both of the above mentioned approaches may permit the design of immunological control measures against this and other related intestinal helminths.